Fluent Essays

1 page memo see attached, 1- an example of the memo 2- the lab manual 3- Video of the lab like of the video https://s3.us-east-1.amazonaws.com/blackboard.learn.xythos.prod/59859110cceba/2669575?response-content-disposition=inline%3B%20filename%2A%3DUTF-8%27%27Lab%252010.mp4&response-content-type=video%2Fmp4&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20200407T005332Z&X-Amz-SignedHeaders=host&X-Amz-Expires=21600&X-Amz-Credential=AKIAIL7WQYDOOHAZJGWQ%2F20200407%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=0dd5089d55ae4519bebbd0357793651f200768fe56778cc1149bd1c1f7b1167f Fields & Equipotentials Class: PHYS xxxxxx xxxxxxxxxxxxxxx Lab Date: xxxxxx Partners: xxxxxxxxxxxxxxxx Memo Date: xxxxxxxxx Instructors: xxxxxxxxxxx The purpose of this lab is to learn how electric fields are created and their effect on charges. An electric field is created by a charge and can be thought of as a region of electrical influence that a charge creates in all the space surrounding itself. In part 1 of this lab we map the electric field of a dipole and in part 2 we calculate electric field and force using a spreadsheet. An electric field E is a vector field giving the force F per unit positive test-charge q0 at each point in space surrounding a charge Q: E=F/q0. This means that an electric field is the region of electrical influence created by charge Q that is characterized by the force per unit charge at each point in space around Q. The size of the electric field at any point is just the size of the force per unit charge at that point and the direction is the direction a positive test charge would move in response to the field. An electric field’s presence can be revealed by the force it exerts on charges placed in the field. The electric potential difference ΔV between two points in an electric field is defined to be the work W per unit test charge q0 required to move a charge between those points: ΔV=W/q0. An equipotential surface is a surface in space over which the electric potential difference between any two points on the surface is zero. Equipotential surfaces and electric fields are always mutually perpendicular. In part 1, we used a battery and conducting paper to generate an electric field of a dipole. To do so, we mapped the field using a voltmeter to measure equipotential lines. We placed a pin on the positive end and another pin on the negative end of the dipole. We then placed another pin along that line between them to find the equipotential lines by finding where the voltmeter read 0 V potential difference giving us a point on that equipotential line for the pin at the place. We then found more points on that equipotential line and then found the potential of that curve. We repeated this moving the pin over one space each time. After completing the graph of equipotential lines we drew in the electric field lines at right angles to the equipotential lines. In part 2, we created a spreadsheet to calculate electric field and force. We used the data from question 1 for the coordinates and charges. We then used Coulomb’s law to calculate the electric field, found the x and y components of the electric field and total electric field, found the magnitude and direction of the total electric field, and then finally calculated the magnitude and direction of force on Qp. The magnitude of force on Qp is -4.47E-03 N and the direction of force on Qp is 153.43. We then used the spreadsheet to find the size and positions of two charges that would exert a force of 1 N at an angle of 225o on a charge of 1 nC located at the origin. We came up with Q1=7.94E-02 C at (1,0) and Q2=7.94E-02 C at (0,1) giving us a magnitude of 1.01 N and a direction of -1350=225o. As the distance between charges increases, the electric field decreases. In this lab, we learned how to find electric fields and equipotential lines using a voltmeter to measure and by using a spreadsheet to calculate using charges and points. Electric fields effect charges by exerting force onto the charge. Department of Physics and Engineering Physics Name Lab Partner Date Sec Lab Partner EXERCISE 10: RL & RLC CIRCUITS PURPOSE In this exercise, you will become familiar with RL & RLC circuits and their behavior. In particular, you will investigate: • exponential current rise and decay in an RL circuit; • damped, oscillatory behavior of an RLC circuit. APPARATUS Function generator, multimeter, resistance box, known capacitor (~550 nF), inductor, oscilloscope and probes, computer and graphical analysis software. PROCEDURE I. RL Circuits: In this part of the exercise, you will build an RL circuit and observe the exponential rise and decay of current predicted by Kirchhoff’s laws. You will measure the circuit’s inductive time constant for both current rise and decay and then use the measurements to calculate the inductance of the inductor. A. Build RL Circuit 1. Assemble the RL circuit shown in Figure 1. Set the decade-resistance box to a resistance Rd of 200 . 2. Use the ohmmeter to measure the resistance of the decade resistance Figure 1: RL Circuit (should be ~200 ) and the resistance RL of the inductor coil; record your measurements below. Rd = RL = 3. Using the information below, determine the output impedance Rgen of your function generator and record below. > Heath-Zenith: square-wave output impedance = 52  on the 0.1 V and 1 V ranges; varies up to 220  on the 10 V range. (So that the Heath-Zenith output impedance doesn’t vary, make sure to set the square-wave output to either the 0.1-V or 1-V range.) > Pasco: output impedance = 600  between the “HI ” (gray) and “GND” (black) terminals. > BK Precision: output impedance = 50 . Rgen = 4. Calculate and record below the total circuit resistance (Rtot); it is the sum of the decade resistance, coil resistance, and signal-generator output impedance. That is, . Rtot = 5. The inductance of the coil is reported by the manufacturer to be ~63 mH. Use this value along with the total circuit resistance to calculate in the space below the expected time constant exp for the circuit. exp = 6. Set the function generator to a square-wave frequency f corresponding to 20 times the time constant exp. (The current will exceed 99% of its final value after 5 time constants. Thus 10 time constants will allow the current to fully rise, then another 10 time constants will allow it to fully decay again. So a frequency corresponding to 20 time constants will allow you to see a complete cycle of the exponential rise and fall of the current.) f = B. Measure coil inductance from inductive time constant 1. Display signal a. Observe the square-wave voltage of the function generator on channel 1 and the circuit current on channel 2. The square-wave voltage output of the signal generator simulates a battery repeatedly turning on and off; use this signal for the oscilloscope trigger signal. Explain how you use the oscilloscope—a voltage-measuring device—to measure current on channel 2. b. Adjust the oscilloscope horizontal sensitivity to display 2-3 periods of the circuit current. The function-generator frequency calculated above should produce a waveform cycle like the middle figure below. If instead each cycle looks like the first or last figure, you will need to adjust the frequency to get the middle display. frequency too low frequency just right frequency too high Now adjust the function generator voltage output and the vertical sensitivity on the current display so that the waveform fills the entire screen (starts on the bottom grid line and ends on the top grid line). 2. Measure the inductive time constant on both the increasing and the decreasing portion of the current cycle. (Recall: the inductive time constant is the amount of time for the current to increase to 63.2% of its final value or decrease to 36.8% of its initial value.) Your results should be similar to the expected time constant you calculated earlier. Now calculate the average of the two measurements. Use this average value to calculate the inductance in the circuit. Record your results: inc = dec = avg = L1 = 3. Change the decade resistance to 1000 ; this will change the circuit time constant and the waveform. Change the frequency of the function generator until the display looks like it did in part B. Position the waveform to display either the increasing or decreasing portion of a current cycle (your choice), starting from the left side of the screen. Measure the time and voltage of the waveform each time it crosses one of the screen’s vertical grid lines. Record these time-voltage data pairs in the table below: Time (s) 0 Voltage (V) 4. Enter the data pairs from the table above into Graphical Analysis; the resulting graph should be a duplicate of the oscilloscope display. In the space below, explain which least-squares curve should be fit to the data and why. Now fit that curve to the data. Annotate and print your graph. Record the resulting least-squares equation below. Use that equation to calculate the time constant for the data. Calculate the coil inductance from this time constant. Make sure to show all calculations. Least-squares equation: ls = L2 = II. RLC Circuits: In this part of the exercise, you will build an RLC circuit and observe the damped oscillations predicted by Kirchhoff’s laws. You will measure the frequency of those oscillations as well as their decay and then use these measurements to calculate the inductance of the inductor. A. Build RLC Circuit 1. Assemble the RLC circuit shown in Figure 2. Set the decade-resistance box to a resistance Rd of 5000 . Set the function generator square-wave output to an initial frequency of 100 Hz. Figure 2: RLC Circuit B. Display signal 1. Observe the square-wave voltage of the function generator on channel 1 and the capacitor voltage on channel 2. The signal on channel 2 should show the damped oscillations (“ringing”) characteristic of an RLC circuit. Note that every time the square wave on channel 1 makes a transition from low to high voltage or vice versa, the capacitor voltage rings: 2. Adjust the square-wave voltage as well as the oscilloscope horizontal and vertical sensitivities to display one set of damped oscillations. Adjust the function generator frequency until the oscillations fully decay; this will allow you to determine the midline of the oscillations. Position the waveform so that the midline of the oscillations begin on the bottom grid line and the highest peak just touches the top grid line at the far left of the screen. When you are done, the display should look something like this: C. Determine coil inductance from oscillation decay 1. Measure the time and voltage of each peak of the waveform. Record these time-voltage data pairs in the table below: Time (s) 0 Voltage (V) 2. Enter the data pairs from the table above into Graphical Analysis. In the space below, explain which least-squares curve should be fit to the data and why. Now fit that curve to the data. Annotate and print your graph. Record the resulting least-squares equation. Least-squares equation: 3. Use the least-squares equation to calculate the inductance of the coil. Very Important: In Figure 2, the portion of the circuit that gives rise to the RLC damped oscillations is the coil and the capacitance. The correct resistance to use in your calculations is the coil resistance RL, not the decade resistance Rd (or any other resistance). L3 = D. Determine coil inductance from oscillation frequency 1. Measure and record the capacitance of the capacitor. Determine the period of the damped oscillations from the data table above. C = = 2. Calculate the inductance of the coil based on your measurements of , RL, and C; show your calculations below (or if you prefer, you can do the work with Mathematica and attach the results to your report.) L4 = E. Summary of Results: List the four independent values for the coil inductance you measured in this exercise and calculate their average and standard deviation. Compare this value with the manufacturer’s value of 63 mH. L1 = L2 = L3 = L4 = Lavg = L = % Error = QUESTIONS 1. Describe the behavior of both the RL and RLC circuit predicted by Kirchhoff’s laws. 2. Comment on how well your data and calculations verified these predictions. Cite specific results. 800 South Tucker Drive • Tulsa, Oklahoma 74104-9700 • 918-631-2517 • www.utulsa.edu An Equal Opportunity/Affirmative Action Employer gen L d tot R R R R + + = Ch 1 (trig) R d L Ch 2 v s (t) coil C R L gnd Ch 1 (trig) Rd L Ch 2 vs(t) coil C RL gnd 0 0.001 0.002 0.003 0.004 0.005 0.2 0.4 0.6 0.8 T ¢ T ¢ L Ch 1 coil R L v s (t) Ch 2 gnd R d L Ch 1 coil RL vs(t) Ch 2 gnd Rd